Ok, Im not saying I am a full pro but I have been doing this for over 20 years and never had this problem before.

Im loading some 45 ACP for my M-10 NFA rig.   I have loaded roughly 3k of various FMJ and plated 230 with no problem at all.

I use a cage gauge (Dillon Gauge) and I get maybe 2or 3 out of 100 that wont go in.  So I toss them into the pull down section.  

I start up loading some (Nevada, west coast, extreme, or whatever they are calling themselves now) 230 LRN.  I adjust the OAL, clean out the dies and inspect then clean my whole 650 then get to town on the load I have worked up before with these.    As Im gauging the first 100 that come out I have a pile of 23 that fail to go in fully.       I clean the gauge then proceed to crank out 100 more to see if I am just feeling strange after the bottle of wine the wife and I shared the evening before.   this time I hit 37 that wont go in.   All are various makes of brass and loaded to correct OAL.

I check the OD and it seems to be spot on 452.   WTF is going on?

I have loaded many 100,000s of various 45 acp in the past and never had this problem.  

Are maybe the bullets out of round causing this.   OF course I dont have my handy dandy concentricty tool anymore.  

Im at a loss.

that being said I loaded up a mag of the "bad" ones just for shits and giggles and dumped them through the mac and they ran fine.
I know stupid but I couldnt figure out what the hell is happening.

just wanted to ad one thing all the brass is pretty damn close to required length

I have that problem with 200g LSWC.  They don't always go into the dillon case gauge.
Of the ones that won't, 2/3-3/4 will run fine in one of my 1911s but NONE of them will work
in my 1911 with a "match" chamber.  I got a Lee factory crimp die, and run all the rounds through it.
Then, they all work in either pistol.  It seems some brass has a problem more than other brands.

try giving them a bit more taper crimp



If they still don't fit the case gage I suspect you have a bunch of beat up brass with dinged rims.  Dinged rims prevent the cases from going into the case gage.  Doublecheck the ones that dont fit the case gage by using an actual pistol barrel

Well I have done this 98% of the rejects fit fine in both my 1911 barrel and my glock 21 barrel.  The rims are not included in this.  I have a small file that I will kiss to the rim if it needs it.  this is happening at the top of the case.  I will give it a bit more taper crimp to see if this is helps.

We will have to see.